1. Technical Field of the Invention
The present invention relates generally to a control information generating apparatus for broadcast systems, and more particularly to a control information generating apparatus for broadcast systems which are designed to transmit audio and video signals and/or teletext signals together with video control information and program information in multiplexed form.
2. Background of Related Art
Usually, when transmitting television programs, a broadcasting station prepares and transmits control information, i.e., EPG (Electronic Program Guide) information for transmission of audio and video signals.
FIG. 1 shows a typical example of such a broadcast system which includes a broadcast database 1, an audio/video data transmitter 2, a control information generator 3, and a multiplexer 4. The broadcast database 1 stores therein television program information. The audio/video data transmitter 2 reads a program schedule and audio/video data out of the broadcast database 1 periodically and transmits them in a data stream form to the multiplexer 4. The control information generator 3 reads program schedule information out of the broadcast database 1, produces control information for each program contained in the program schedule information, and transmits it in a data stream form to the multiplexer 4. The multiplexer 4 multiplexes the audio/video data from the audio/video transmitter 2 and the control information from the control information generator 3 to output them on a broadcast wave.
The control information generator 3 includes, as shown in FIG. 2, a control data generating circuit 5. The control data generating circuit 5 consists of a schedule database 7, a sequential data generator 8, and an output circuit 9. The schedule database 7 stores therein the program schedule information read out of the broadcast database 1. The sequential data generator 8 controls reception of the program schedule information from the broadcast database 1 in the schedule database 7 and processes the information stored in the schedule database 7 in sequence to produce control data components. The output circuit 9 transmits the control data components to the multiplexer 4.
The output circuit 9 consists of a plurality of data output units (only three 9a, 9b, and 9c are shown in FIG. 2 for the brevity of illustration). FIG. 3 shows one of the data output units 9a to 9b which includes an input circuit 10 receiving the control data components coming from the sequential data generator 8, a storage device 11 storing therein the received control data, an output circuit 12 outputting the control data components stored in the storage device 11, and a scheduler 13 controlling reading of the control data components from the storage device 11.
The data output units 9a to 9c receive the control data components from the sequential data generator 8 and output them in parallel to the multiplexer 4. The storage device 11 of each of the data output units 9a to 9c stores the control data component as a plurality of tables (e.g., 400 tables: PAT, PMT0, PMT1, TMT2, PMT3, . . . ) and output the tables in response to a command from the scheduler 13.
The above conventional broadcast system, however, encounters the following drawback.
The control information generator 3 must receive a large amount of the program schedule information and perform in a CPU a large number of operations to generate the control data components, which will result in a delay in output from the CPU and also make it difficult to increase the accuracy of transmission cycles of the control data components. For example, when the number of tables stored in the storage device 11 exceeds 1,000, it will cause an operational load of the output circuit 9 to be increased, thus resulting in delay in output from the output circuit 9.
It is therefore a principal object of the present invention to avoid the disadvantages of the prior art.
It is another object of the present invention to provide a control information generating apparatus for broadcast systems which is capable of altering program control information without interrupting a system operation to output audio/video data.
It is a further object of the present invention to provide a control information generating apparatus for broadcast systems which is capable of altering a TV program schedule at regular intervals and taking measures to meet unexpected program change requirements.
According to one aspect of the present invention, there is provided a control information generating apparatus for use in a broadcast system including a broadcast database storing therein program information and an audio/video data transmitter. The control information generating apparatus receives a program schedule and audio/video data from the broadcast database and transmits a data signal thereof and a multiplexer and comprises: (a) a control information generating circuit which receives program schedule information on a program from the broadcast database to generate control information on a program of the program schedule information and outputs a signal of the control information; and (b) a control information outputting circuit which receives the signal of the control information from the control information generating circuit and outputs the control information to the multiplexer in which the control information and the data signal from the audio/video data transmitter are multiplexed.
In the preferred mode of the invention, the control information generating circuit includes an input circuit which receives the program schedule information from the broadcast database, a version generator which receives the program schedule information from the input circuit to generate table information and assigns a version number to the table information, a TS packetizing circuit which packetizes the table information outputted from the version generator, a bandwidth adjuster which determines a transmission cycle of the table information so that all the table information may be transmitted for adjusting a transmission bandwidth thereof, and an output circuit which outputs the table information to the control information outputting circuit.
The control information outputting circuit includes an input circuit which receives the control information outputted from the control information generating circuit, a storage device which stores the control information in grouped table forms, an output circuit which outputs the control information stored in the storage device, and a scheduler which controls timing where the control information is outputted from the storage device to the output circuit.
The program schedule information consists of a PSI element and an SI element which are transmitted independently from the broadcast database to the control information generating circuit.
The program schedule information is provided in units of a file containing programs for one day broadcasted through all services.
The version generator sections a schedule database prepared by the input circuit in units of a table to produce table information elements and assigns consecutive version numbers at least one to each of the table information elements. The version generator includes a version skip detecting circuit detecting a skip of the version numbers.
The control information outputting circuit may include a plurality of control information outputting units. The control information outputting units are controlled so that the control information being transmitted currently will be updated simultaneously at a switching time that is a current time plus a marginal time.
The bandwidth adjuster includes a bandwidth adjustment table for determining a bandwidth adjustable range and changing the degree of bandwidth adjustment according to a property of each table of the table information.
From some of the table information elements having the different version numbers which are to be transmitted within a given period of time, one having the greatest amount of data is extracted as an object of determination of the transmission cycle.
The control information generating circuit classifies the control information to be stored in the storage device of the control information outputting circuit into groups in units of a transmitted data element according to one of a transmission cycle and an information updating time.
The table information is supplied from the control information generating circuit in the grouped table form.
The storage device may include a pre-storage, a post-storage, and a table combiner. The pre-storage stores therein the table information in units of a table. The table combiner combines tables stored in the pre-storage into table groups a preselected time before the table groups are outputted from the output circuit. The post-storage stores therein the table groups provided by the table combiner.
The table combiner may combine some of tables into table groups a preselected time before all table groups are outputted from the output circuit.
The control information includes tables each consisting of sub-tables each consisting of sections. The transmitted data element in each of the groups consists of the sections having the same section number. The transmitted data elements are transmitted at given time intervals.
The output circuit includes a plurality of cues having different output priorities, respectively. Each cue stores therein the control information in a grouped table form. The output circuit reads tables out of one of the cues having a higher degree of output priority.
According to the second aspect of the invention, there is provided a control information generating apparatus for use in a broadcast system which comprises: (a) a control information generating circuit which receives program schedule information on a program to generate control information on the program and outputs a signal indicative of the control information, the control information generating circuit including an input circuit, a table preparing circuit, and an output circuit, the input circuit receiving the schedule information, the table preparing circuit preparing table information as the control information based on the program schedule information, the output circuit outputting a signal indicative of the table information; and (b) a control information outputting circuit including an input circuit, a version management circuit, a TS packetizing circuit, a bandwidth adjusting circuit, a storage device, a scheduler, and an output circuit, the input circuit receiving the signal indicative of the table information from the control information generating circuit, the version management circuit assigning a version number to the table information, the TS packetizing circuit packetizing the table information, the bandwidth adjusting circuit determining a transmission bandwidth and a transmission cycle of the table information, the storage device storing therein the table information in packet form, the scheduler controlling output timing with which the table information stored in the storage device is outputted from the output circuit according to the transmission cycle determined by the bandwidth adjusting circuit.
In the preferred mode of the invention, the program schedule information has areas for writing therein an alternation date on which the program schedule information was altered and a reception date on which the control information generating circuit received the program schedule information. The control information generating circuit looks up the program schedule information to know a newly altered portion of the program schedule information.
The table preparing circuit stores therein a version number-information element table listing a relation between version numbers and information elements of table information. When assigning the version number to the table information, the version management circuit looks up the version number-information element table stored in the table preparing circuit to obtain one of the information elements corresponding to the version number and to add the one of the information elements to one of information elements of the table information prepared by the table preparing circuit.
The information elements listed in the version number-information element table are cyclic redundancy checks.
The input circuit of the control information outputting circuit includes a memory management circuit which monitors an available memory capacity of the control information outputting circuit to provide a signal indicative thereof to the control information generating circuit. The control information generating circuit is responsive to the signal from the memory management circuit to supply the table information of an amount within the available memory capacity of the control information outputting circuit.
The output circuit of the control information generating circuit may be provided independently from the control information generating circuit as functioning as a control information transferring circuit which manages only data transfer from the control information generating circuit to the control information outputting circuit.
The control information outputting circuit may include a plurality of control information outputting units each designed to output the table information to a corresponding transponder. Each of the control information outputting units provides a signal to the control information generating circuit indicating completion of preparation of output of the table information. When the control information generating circuit has received the signals from all the control information outputting units, the control information generating circuit provides output enable signals to the control information outputting units to allow the control information outputting units to output the table information simultaneously.
The table information includes sub-tables each consisting of sections. The TS packetizing circuit assigns the sections of one of the sub-tables to different groups, respectively, and packetizes the table information in each of the groups.
The table preparing circuit may prepare the table information within a set time and also prepares spare table information on a subsequent program within an additional time following the set time. The control information outputting circuit stores the table information and the spare table information.
The table information includes a plurality of table information elements. A means may further be provided for designating one of the table information elements to be outputted from the control information outputting circuit.
The table information is formed with a plurality of transport streams. A means may further be provided for bearing a relation between one of the transport streams and each of the control information outputting units to specify one of the control information outputting units to which each of the transport streams is to be assigned.
A means may further be provided for determining cycles of transmission of the table information from the control information outputting units in units of a transponder.
A means may further be provided for determining bandwidths of transmission of the table information from the control information outputting units in units of a transponder.
A means may further be provided for determining bandwidths of transmission of the table information from the control information outputting units in units of a service.
A means may further be provided for supplying a dummy transport stream to one of the control information outputting units to prohibit output of the table information therefrom, thereby allowing a TV program schedule of another network to be transmitted.
The control information generating circuit receives the program schedule information from a broadcast database. The control information generating circuit is responsive to a non-output command signal inputted from an external device to prepare and return the table information to the broadcast database without outputting the table information to the control information outputting circuit.
The control information outputting circuit is also responsive to an output time designation signal inputted from an external device to transmit the control information at designated date and time.
An urgent alternation requesting circuit may further be provided which is responsive to an urgent alternation request signal outputted from the broadcast database to prohibit preparation of the table information in the control information generating circuit for altering the table information.
The table information may have free format regions.
The table information may also have table analysis information regions for storing therein table analysis information for analysis of table information elements of the table information prepared in free formats for allowing formats of all the table information elements to be determined through an external device without fixing the formats of all the table information elements in advance.
According to the third aspect of the invention, there is provided a control information generating apparatus for use in a broadcast system which comprises: (a) a control information generating circuit which receives program schedule information on a program to generate control information on the program and outputs a signal indicative of the control information, the control information generating circuit including an input circuit, a table preparing circuit, a version management circuit, a TS packetizing circuit, a bandwidth adjusting circuit, and an output circuit, the input circuit receiving the schedule information, the table preparing circuit preparing table information as the control information based on the program schedule information, the version management circuit assigning at least one of consecutive version numbers to the table information prepared by the table preparing circuit, the TS packetizing circuit packetizing the table information to which the version number is assigned, the bandwidth adjusting circuit determining a transmission bandwidth and a transmission cycle of the table information, the output circuit outputting the signal indicative of the table information; and (b) control information outputting circuits each including an input circuit, a storage device, a scheduler, and an output circuit, the input circuit receiving the signal indicative of the table information from the control information generating circuit, the storage device storing therein the table information inputted through the input circuit, the scheduler controlling output timing of the table information stored in the storage device from the output circuit according to the transmission cycle determined by the bandwidth adjusting circuit of the control information generating circuit.
The control information outputting circuits are provided one for each transponder.
When it becomes impossible for the version management circuit to know the version number to be assigned to the table information, the version management circuit may assign the consecutive version numbers, in sequence, to the table information from first one of the consecutive version numbers and output the table information through the output circuit in sequence.
The table preparing circuit prepares table information elements, in sequence, as the control information. The version management circuit assigns the consecutive version numbers, in sequence, at least one for each of the table information elements. The output circuit of the control information generating circuit outputs signals indicative of the table information elements to the control information outputting circuits. When a version number skip has occurred when the version management circuit assigns the version numbers to the table information elements, the version management circuit determines the greater of a version number assigned to the table information element that was last successful in being supplied to the control information outputting circuits and a version number following omitted one of the consecutive version numbers as a maximum value and the smaller thereof as an initial value and reassigns ones of the consecutive version numbers between the initial value and the maximum value, in sequence, to one of the table information elements when the version number skip has occurred.
The version management circuit determines a period of time during which it is possible for the input circuit of each of the control information outputting circuits to receive the table information element to which one following a version number assigned to the information element being received currently by the input circuit is assigned, the version management circuit determines that a version number skip will occur in the table information elements when outputted from the output circuit of each of the control information outputting circuits if the input circuit has not received within the determined period of time the table information element to which the one following the version number assigned to the information element being received currently by the input circuit is assigned.
The version management circuit determines a period of time during which it is possible for the input circuit of each of the control information outputting circuits to receive the table information element to which one following a version number assigned to the information element being received currently by the input circuit is assigned, the output circuit of the control information generating circuit may determine that a version number skip will occur in the table information elements when outputted from the output circuit of each of the control information outputting circuits if the output circuit of the control information generating circuit has not outputted within the determined period of time the table information element to which the one following the version number assigned to the information element being received currently by the input circuit of each of the control information outputting circuits is assigned.
The table information includes sub-tables each consisting of sections. The TS packetizing circuit assigns the sections of one of the sub-tables to different groups, respectively, and packetizes the sections in each of the groups.
The scheduler of each of the control information outputting circuits ensures minimum transmission intervals at which the table information is transmitted from each of the control information outputting circuits in units of the groups.
The sections of the sub-tables are grouped in units of a section number.
The TS packetizing circuit is designed to determine whether the table information has versions greater than a given value or not.
When it is determined that the table information has the versions greater than the given value, the TS packetizing circuit provides a packetizing schedule to each of the control information outputting circuits without packetizing the table information. Each of the control information outputting circuits packetizes the information table according to the packetizing schedule.
The TS packetizing circuit may assign the sections of the sub-tables to different groups in units of a transport stream and packetizes the sections in each of the groups.
The table preparing circuit may prepare the table information within a set time and also prepare spare table information on a subsequent program within an additional time following the set time. Each of the control information outputting circuits stores the table information and the spare table information.
The table information includes a plurality of table information elements. A means may further be provided for designating one of the table information elements to be outputted from each of the control information outputting circuits.
The table information is formed with a plurality of transport streams. A means may further be provided for bearing a relation between one of the transport streams and each of the control information outputting circuits to specify one of the control information outputting circuits to which each of the transport streams is to be assigned.
The control information outputting circuits are provided one for each transponder. A means may further be provided for determining cycles of transmission of the table information from the control information outputting circuits in units of a transponder.
A means may further be provided for determining bandwidths of transmission of the table information from the control information outputting circuits in units of a transponder.
A means may further be provided for determining bandwidths of transmission of the table information from the control information outputting circuits in units of a service.
A means may further be provided for supplying a dummy transport stream to one of the control information outputting circuits to prohibit output of the table information therefrom, thereby allowing a TV program schedule of another network to be transmitted.
The control information generating circuit receives the program schedule information from a broadcast database. The control information generating circuit is responsive to a non-output command signal inputted from an external device to prepare and return the table information to the broadcast database without outputting the table information to the control information outputting circuits.
Each of the control information outputting circuits is responsive to an output time designation signal inputted from an external device to transmit the control information at designated date and time.
An urgent alternation requesting circuit may further be provided which is responsive to an urgent alternation request signal from the broadcast database to prohibit preparation of the table information in the control information generating circuit for altering the table information.
The table information has free format regions.
The table information has table analysis information regions for storing therein table analysis information for analysis of table information elements of the table information prepared in free formats for allowing formats of all the table information elements to be determined through an external device without fixing the formats of all the table information elements in advance.
According to the fourth aspect of the invention, there is provided a control information generating apparatus for use in a broadcast system which comprises: (a) a main control information generating circuit which receives program schedule information on a program from a broadcast database to generate control information on the program and outputs a signal indicative of the control information, the control information generating circuit including an input circuit, a table preparing circuit, and an output circuit, the input circuit receiving the schedule information, the table preparing circuit preparing table information as the control information based on the program schedule information, the output circuit outputting a signal indicative of the table information; (b) a sub-control information generating circuit which receives the program schedule information from the broadcast database to generate the control information and outputs a signal indicative of the control information, the control information generating circuit including an input circuit, a table preparing circuit, and an output circuit, the input circuit receiving the schedule information, the table preparing circuit preparing table information as the control information based on the program schedule information, the output circuit outputting a signal indicative of the table information; (c) a main control information outputting circuit including an input circuit, a common version management circuit, a TS packetizing circuit, a bandwidth adjusting circuit, a storage device, a scheduler, and an output circuit, the input circuit receiving the signals indicative of the table information from the main and sub-control information generating circuits, the common version management circuit assigning a version number to the table information, the TS packetizing circuit packetizing the table information, the bandwidth adjusting circuit determining a transmission bandwidth and a transmission cycle of the table information, the storage device storing therein the table information in packet form, the scheduler controlling output timing of the table information stored in the storage device from the output circuit according to the transmission cycle determined by the bandwidth adjusting circuit; and (d) a sub-control information outputting circuit including an input circuit, the common version management circuit, a TS packetizing circuit, a bandwidth adjusting circuit, a storage device, a scheduler, and an output circuit, the input circuit receiving the signal indicative of the table information from the control information generating circuit, the TS packetizing circuit packetizing the table information, the bandwidth adjusting circuit determining a transmission bandwidth and a transmission cycle of the table information, the storage device storing therein the table information in packet form, the scheduler controlling output timing of the table information stored in the storage device from the output circuit according to the transmission cycle determined by the bandwidth adjusting circuit.
According to the fifth aspect of the invention, there is provided a control information generating apparatus for use in a broadcast system which comprises: (a) a control information generating circuit which receives program schedule information on a program from a broadcast database to generate control information on the program and outputs a signal indicative of the control information, the control information generating circuit including an input circuit, a table preparing circuit, a common version management circuit, a TS packetizing circuit, a bandwidth adjusting circuit, and an output circuit, the input circuit receiving the schedule information, the table preparing circuit preparing table information as the control information based on the program schedule information, the version management circuit assigning at least one of consecutive version numbers to the table information prepared by the table preparing circuit, the TS packetizing circuit packetizing the table information to which the version number is assigned, the bandwidth adjusting circuit determining a transmission bandwidth and a transmission cycle of the table information, the output circuit outputting the signal indicative of the table information; (b) a sub-control information generating circuit which receives the program schedule information from the broadcast database to generate the control information on the program and outputs a signal indicative of the control information, the control information generating circuit including an input circuit, a table preparing circuit, the common version management circuit, a TS packetizing circuit, a bandwidth adjusting circuit, and an output circuit, the input circuit receiving the schedule information, the table preparing circuit preparing table information as the control information based on the program schedule information, the TS packetizing circuit packetizing the table information to which the version number is assigned by the common version management circuit, the bandwidth adjusting circuit determining a transmission bandwidth and a transmission cycle of the table information, the output circuit outputting the signal indicative of the table information; (c) a main control information outputting circuit including an input circuit, a storage device, a scheduler, and an output circuit, the input circuit receiving the signals indicative of the table information from the main and sub-control information generating circuits, the storage device storing therein the table information inputted through the input circuit, the scheduler controlling output timing of the table information stored in the storage device from the output circuit according to the transmission cycle determined by the bandwidth adjusting circuit of the control information generating circuit; and (d) a sub-control information outputting circuit including an input circuit, a storage device, a scheduler, and an output circuit, the input circuit receiving the signals indicative of the table information from the main and sub-control information generating circuits, the storage device storing therein the table information inputted through the input circuit, the scheduler controlling output timing of the table information stored in the storage device from the output circuit according to the transmission cycle determined by the bandwidth adjusting circuit of the control information generating circuit.